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Subject[PATCH 13/16] x86: Remove cpumask games in x86/kernel/cpu/intel_cacheinfo.c
Impact: remove cpumask_t from stack.

We should not try to save and restore cpus_allowed on current.

We can't use work_on_cpu() here, since it's in the hotplug cpu path
(if anyone else tries to get the hotplug lock from a workqueue we
could deadlock against them).

Fortunately, we can just use smp_call_function_single() since the
function can run from an interrupt.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
---
arch/x86/kernel/cpu/intel_cacheinfo.c | 41 +++++++++++++++-----------------
1 files changed, 19 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 43ea612..fb7f946 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -534,31 +534,16 @@ static void __cpuinit free_cache_attributes(unsigned int cpu)
per_cpu(cpuid4_info, cpu) = NULL;
}

-static int __cpuinit detect_cache_attributes(unsigned int cpu)
+static void get_cpu_leaves(void *_retval)
{
- struct _cpuid4_info *this_leaf;
- unsigned long j;
- int retval;
- cpumask_t oldmask;
-
- if (num_cache_leaves == 0)
- return -ENOENT;
-
- per_cpu(cpuid4_info, cpu) = kzalloc(
- sizeof(struct _cpuid4_info) * num_cache_leaves, GFP_KERNEL);
- if (per_cpu(cpuid4_info, cpu) == NULL)
- return -ENOMEM;
-
- oldmask = current->cpus_allowed;
- retval = set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
- if (retval)
- goto out;
+ int j, *retval = _retval, cpu = smp_processor_id();

/* Do cpuid and store the results */
for (j = 0; j < num_cache_leaves; j++) {
+ struct _cpuid4_info *this_leaf;
this_leaf = CPUID4_INFO_IDX(cpu, j);
- retval = cpuid4_cache_lookup(j, this_leaf);
- if (unlikely(retval < 0)) {
+ *retval = cpuid4_cache_lookup(j, this_leaf);
+ if (unlikely(*retval < 0)) {
int i;

for (i = 0; i < j; i++)
@@ -567,9 +552,21 @@ static int __cpuinit detect_cache_attributes(unsigned int cpu)
}
cache_shared_cpu_map_setup(cpu, j);
}
- set_cpus_allowed_ptr(current, &oldmask);
+}
+
+static int __cpuinit detect_cache_attributes(unsigned int cpu)
+{
+ int retval;
+
+ if (num_cache_leaves == 0)
+ return -ENOENT;
+
+ per_cpu(cpuid4_info, cpu) = kzalloc(
+ sizeof(struct _cpuid4_info) * num_cache_leaves, GFP_KERNEL);
+ if (per_cpu(cpuid4_info, cpu) == NULL)
+ return -ENOMEM;

-out:
+ smp_call_function_single(cpu, get_cpu_leaves, &retval, true);
if (retval) {
kfree(per_cpu(cpuid4_info, cpu));
per_cpu(cpuid4_info, cpu) = NULL;
--
1.6.0
--


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